#define _CRT_SECURE_NO_WARNINGS 1

#include<iostream>
#include<algorithm>
#include<vector>

using namespace std;

vector<int> numberGame(vector<int>& nums) {
    sort(nums.begin(), nums.end());
    for (int i = 0; i < nums.size(); i += 2)
        swap(nums[i], nums[i + 1]);

    return nums;
}